Method of making a piezoelectric mems diaphragm microphone

ABSTRACT

A piezoelectric microelectromechanical systems diaphragm microphone can be mounted on a printed circuit board. The microphone can include a substrate with an opening between a bottom end of the substrate and a top end of the substrate. The microphone can have two or more piezoelectric film layers disposed over the top end of the substrate and defining a diaphragm structure. Each of the two or more piezoelectric film layers can have a predefined residual stress that substantially cancel each other out so that the diaphragm structure is substantially flat with substantially zero residual stress. The microphone can include one or more electrodes disposed over the diaphragm structure. The diaphragm structure is configured to deflect when the diaphragm is subjected to sound pressure via the opening in the substrate.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication, including U.S. patent application Ser. No. 16/890,858,filed Jun. 2, 2020 and titled “PIEZOELECTRIC MEMS DIAPHRAGM MICROPHONE”,U.S. Provisional Patent Application No. 62/857,675, filed Jun. 5, 2019and titled “PIEZOELECTRIC MEMS DIAPHRAGM MICROPHONE,” and U.S.Provisional Patent Application No. 62/857,701, filed Jun. 5, 2019 andtitled “METHOD OF MAKING A PIEZOELECTRIC MEMS DIAPHRAGM MICROPHONE,” arehereby incorporated by reference under 37 CFR 1.57.

BACKGROUND Field

The present disclosure is directed to a piezoelectricmicroelectromechanical systems (MEMS) microphone, and in particular to amulti-layer piezoelectric MEMS diaphragm microphone.

Description of the Related Art

A MEMS microphone is a micro-machined electromechanical device used toconvert sound pressure (e.g., voice sound) to an electrical signal(e.g., voltage). MEMS microphones are widely used in mobile devices,headsets, smart speakers and other voice-interface devices or systems.Conventional capacitive MEMS microphones suffer from high powerconsumption (e.g., large bias voltage) and reliability, for example whenused in a harsh environment (e.g., when exposed to dust and/or water).

Piezoelectric MEMS microphones have been used to address thedeficiencies of capacitive MEMS microphones. Piezoelectric MEMSmicrophones offer a constant listening capability while consuming almostno power (e.g., no bias voltage is needed), are robust and immune towater and dust contamination. Existing piezoelectric MEMS microphonesare based on either a cantilever MEMS structure or a diaphragm MEMSstructure.

The cantilever MEMS structure suffers from poor low-frequency roll-offcontrol as the gap between cantilevers varies when cantilevers deflectdue to residual stress. Additionally, the cantilever MEMS structure withgap control mechanism can have a complex structure that results inhigher manufacturing costs and poor reliability performance. Thediaphragm MEMS structure provides better low-frequency roll-off controland higher sensitivity than the cantilever MEMS structure, but suffersfrom sensitivity variation as residual stress causes large tensile orcompression stresses within the diaphragm (e.g., a small residual stressresults in a large sensitivity degradation for diaphragm typepiezoelectric MEMS microphone).

SUMMARY OF CERTAIN INVENTIVE ASPECTS

Accordingly, there is a need for an improved piezoelectric MEMSmicrophone that does not suffer the deficiencies in existing MEMScantilever and diaphragm structures.

In accordance with one aspect of the disclosure, amulti-piezoelectric-layer MEMS diaphragm microphone is provided thatsubstantially cancels the overall residual stress in the diaphragm. Themulti-piezoelectric-layer MEMS diaphragm microphone advantageouslyprovides higher sensitivity (e.g., how much voltage is measured whendiaphragm is provided to sound pressure) and better lower frequencyroll-off as compared to the MEMS cantilever structure. Themulti-piezoelectric-layer MEMS diaphragm microphone can optionallyinclude two or more piezoelectric films with predefined residual stress(e.g., during film deposition) that substantially balance (e.g., cancel)out residual stress in the diaphragm structure.

In accordance with one aspect of the disclosure, a piezoelectricmicroelectromechanical systems diaphragm microphone is provided. Themicrophone can include a substrate defining an opening between a bottomend of the substrate and a top end of the substrate. The microphone canalso include two or more piezoelectric film layers disposed over the topend of the substrate and defining a diaphragm structure. Each of the twoor more piezoelectric film layers has a predefined residual stress thatsubstantially cancel each other out so that the diaphragm structure issubstantially flat with substantially zero residual stress. Themicrophone also comprises one or more electrodes disposed over thediaphragm structure. The diaphragm structure is configured to deflectwhen the diaphragm is subjected to sound pressure via the opening in thesubstrate.

In an embodiment, the diaphragm structure has a circular shape. The oneor more electrodes that are disposed over the diaphragm structure caninclude a circumferential electrode that is disposed over acircumference of the diaphragm structure and a center electrode that isdisposed generally over a center of the diaphragm structure. At least aportion of the center electrode can be spaced apart from thecircumferential electrode.

In an embodiment, the diaphragm structure has a rectangular shape. Theone or more electrodes that is disposed over the diaphragm structure caninclude a plurality of side electrodes that are disposed adjacentcorresponding side edges of the diaphragm structure. The plurality ofside electrodes can be spaced apart from each other and disposed aroundan area of the diaphragm structure that extends between the plurality ofside electrodes.

In an embodiment, each of the one or more electrodes is divided into twoor more electrode portions by one or more gaps between the electrodeportions to provide a microphone with a desired sensitivity andcapacitance. Each pair of the two or more electrode portions can beconnected in series by a connection via.

In an embodiment, the microphone further includes a through hole in thediaphragm structure that extends from a top surface of the diaphragmstructure to a bottom surface of the diaphragm structure. The throughhole can be configured to define a low frequency roll off for themicrophone.

In an embodiment, the microphone further includes a bottom electrodethat is interposed between the substrate and two or more piezoelectricfilm layers, and a middle electrode that is interposed between two ofthe two or more piezoelectric film layers.

In accordance with another aspect of the disclosure, a radiofrequencymodule is provided. The radiofrequency module can include a printedcircuit board including a substrate layer. The radiofrequency module canalso include one or more piezoelectric microelectromechanical systemsdiaphragm microphones mounted on the printed circuit board. Eachmicrophone includes a substrate defining an opening between a bottom endof the substrate and a top end of the substrate, and two or morepiezoelectric film layers disposed over the top end of the substrate anddefining a diaphragm structure. Each of the two or more piezoelectricfilm layers has a predefined residual stress that substantially canceleach other out so that the diaphragm structure is substantially flatwith substantially zero residual stress. One or more electrodes aredisposed over the diaphragm structure. The diaphragm structure isconfigured to deflect when the diaphragm is subjected to sound pressurevia the opening in the substrate.

In an embodiment, the diaphragm structure has a circular shape. The oneor more electrodes that are disposed over the diaphragm structure caninclude a circumferential electrode that is disposed over acircumference of the diaphragm structure and a center electrode that isdisposed generally over a center of the diaphragm structure. At least aportion of the center electrode can be spaced apart from thecircumferential electrode.

In an embodiment, the diaphragm structure has a rectangular shape. Thediaphragm structure can have a square shape. The one or more electrodesthat are disposed over the diaphragm structure can include a pluralityof side electrodes that are disposed adjacent corresponding side edgesof the diaphragm structure. The plurality of side electrodes can bespaced apart from each other and disposed around an area of thediaphragm structure that extends between the plurality of sideelectrodes.

In an embodiment, each of the one or more electrodes is divided into twoor more electrode portions by one or more gaps between the electrodeportions to provide a microphone with a desired sensitivity andcapacitance. Each pair of the two or more electrode portions can beconnected in series by a connection via.

In an embodiment, the radiofrequency module further includes a throughhole in the diaphragm structure that extends from a top surface of thediaphragm structure to a bottom surface of the diaphragm structure. Thethrough hole can be configured to define a low frequency roll off forthe microphone.

In an embodiment, the radiofrequency module further includes a bottomelectrode that is interposed between the substrate and two or morepiezoelectric film layers, and a middle electrode that is interposedbetween two of the two or more piezoelectric film layers.

In accordance with another aspect of the disclosure, a wireless mobiledevice is provided. The wireless mobile device can include one or moreantennas, a front end system that communicates with the one or moreantennas, and one or more one or more piezoelectricmicroelectromechanical systems diaphragm microphones mounted on asubstrate layer. Each microphone includes a substrate defining anopening between a bottom end of the substrate and a top end of thesubstrate, and two or more piezoelectric film layers disposed over thetop end of the substrate and defining a diaphragm structure. Each of thetwo or more piezoelectric film layers has a predefined residual stressthat substantially cancel each other out so that the diaphragm structureis substantially flat with substantially zero residual stress. One ormore electrodes are disposed over the diaphragm structure. The diaphragmstructure is configured to deflect when the diaphragm is subjected tosound pressure via the opening in the substrate.

In an embodiment, the diaphragm structure has a circular shape. The oneor more electrodes that are disposed over the diaphragm structure caninclude a circumferential electrode that is disposed over acircumference of the diaphragm structure and a center electrode that isdisposed generally over a center of the diaphragm structure. At least aportion of the center electrode can be spaced apart from thecircumferential electrode.

In an embodiment, the diaphragm structure has a rectangular shape. Thediaphragm structure can have a square shape. The one or more electrodesthat are disposed over the diaphragm structure can include a pluralityof side electrodes that are disposed adjacent corresponding side edgesof the diaphragm structure. The plurality of side electrodes can bespaced apart from each other and disposed around an area of thediaphragm structure that extends between the plurality of sideelectrodes.

In an embodiment, each of the one or more electrodes is divided into twoor more electrode portions by one or more gaps between the electrodeportions to provide a microphone with a desired sensitivity andcapacitance. Each pair of the two or more electrode portions can beconnected in series by a connection via.

In an embodiment, the wireless mobile device further includes a throughhole in the diaphragm structure that extends from a top surface of thediaphragm structure to a bottom surface of the diaphragm structure. Thethrough hole can be configured to define a low frequency roll off forthe microphone.

In an embodiment, the wireless mobile device further includes a bottomelectrode that is interposed between the substrate and two or morepiezoelectric film layers, and a middle electrode that is interposedbetween two of the two or more piezoelectric film layers.

In accordance with another aspect of the disclosure, a method of makinga piezoelectric microelectromechanical systems diaphragm microphone isprovided. The method can include the steps of: a) oxidizing a topsurface and a bottom surface of a substrate to form a top oxidationlayer and a bottom oxidation layer, b) forming or applying two or morepiezoelectric film layers over the top surface of the substrate so thateach of the two or more piezoelectric film layers has a predefinedresidual stress that substantially cancel each other out, the two ormore piezoelectric film layers defining a substantially flat diaphragmstructure with substantially zero residual stress, c) forming orapplying one or more electrodes over the two or more piezoelectric filmlayers, and d) etching the bottom oxidation layer and substrate to forman opening in the substrate that allows sound pressure to travel throughthe opening to deflect the diaphragm structure.

In an embodiment, the diaphragm structure has a circular shape. Formingor applying the one or more electrodes over the two or morepiezoelectric film layers can include forming or applying acircumferential electrode over a circumference of the diaphragmstructure and forming or applying a center electrode generally over acenter of the diaphragm structure. At least a portion of the centerelectrode can be spaced apart from the circumferential electrode.

In an embodiment, the diaphragm structure has a rectangular shape.Forming or applying the one or more electrodes over the two or morepiezoelectric film layers can include forming or applying a plurality ofside electrodes disposed adjacent corresponding side edges of thediaphragm structure. The plurality of side electrodes can be spacedapart from each other and disposed around an area of the diaphragmstructure that extends between the plurality of side electrodes.

In an embodiment, the method further includes dividing the one or moreelectrodes into two or more electrode portions by forming one or moregaps between the electrode portions to provide a microphone with adesired sensitivity and capacitance. The method can further includeconnecting each pair of the two or more electrode portions in serieswith a connection via.

In an embodiment, the method further includes forming a through hole inthe diaphragm structure from a top surface of the diaphragm structure toa bottom surface of the diaphragm structure to define a low frequencyroll off for the microphone.

In an embodiment, the method further includes forming or applying abottom electrode over the top surface of the substrate prior to formingor applying the two or more piezoelectric film layers. The method canfurther includes forming or applying a middle electrode between two ofthe two or more piezoelectric film layers.

In an embodiment, the method further includes forming or applying apassivation layer over the one or more electrodes that is disposed overthe two or more piezoelectric film layers.

In an embodiment, forming or applying two or more piezoelectric filmlayers over the top surface of the substrate so that each of the two ormore piezoelectric film layers has a predefined residual stress thatsubstantially cancel each other out includes controlling one or both ofa pressure and a bias voltage during a deposition process for the eachof the two or more piezoelectric film layers

In accordance with another aspect of the disclosure, a method of makinga radiofrequency module is provided. The method can include the steps offorming or providing a printed circuit board that includes a substratelayer, and forming or providing one or more piezoelectricmicroelectromechanical systems diaphragm microphones. The process offorming or providing one or more piezoelectric microelectromechanicalsystems diaphragm microphones can include: (a) oxidizing a top surfaceand a bottom surface of a substrate to form a top oxidation layer and abottom oxidation layer, (b) forming or applying two or morepiezoelectric film layers over the top surface of the substrate so thateach of the two or more piezoelectric film layers has a predefinedresidual stress that substantially cancel each other out, the two ormore piezoelectric film layers defining a substantially flat diaphragmstructure with substantially zero residual stress, (c) forming orapplying one or more electrodes over the two or more piezoelectric filmlayers, and (d) etching the bottom oxidation layer and substrate to forman opening in the substrate that allows sound pressure to travel throughthe opening to deflect the diaphragm structure. The method of making theradiofrequency module also comprises the step of mounting the one ormore piezoelectric microelectromechanical systems diaphragm microphoneson the printed circuit board.

In an embodiment, the diaphragm structure has a circular shape. Formingor applying the one or more electrodes over the two or morepiezoelectric film layers can include forming or applying acircumferential electrode over a circumference of the diaphragmstructure and forming or applying a center electrode generally over acenter of the diaphragm structure. At least a portion of the centerelectrode can be spaced apart from the circumferential electrode.

In an embodiment, the diaphragm structure has a rectangular shape.Forming or applying the one or more electrodes over the two or morepiezoelectric film layers can include forming or applying a plurality ofside electrodes disposed adjacent corresponding side edges of thediaphragm structure. The plurality of side electrodes can be spacedapart from each other and disposed around an area of the diaphragmstructure that extends between the plurality of side electrodes.

In an embodiment, the method further includes dividing the one or moreelectrodes into two or more electrode portions by forming one or moregaps between the electrode portions to provide a microphone with adesired sensitivity and capacitance. The method can further includeconnecting each pair of the two or more electrode portions in serieswith a connection via.

In an embodiment, the method further includes forming a through hole inthe diaphragm structure from a top surface of the diaphragm structure toa bottom surface of the diaphragm structure to define a low frequencyroll off for the microphone.

In an embodiment, the method further includes forming or applying abottom electrode over the top surface of the substrate prior to formingor applying the two or more piezoelectric film layers. The method canfurther include forming or applying a middle electrode between two ofthe two or more piezoelectric film layers.

In an embodiment, the method further includes forming or applying apassivation layer over the one or more electrodes that are disposed overthe two or more piezoelectric film layers.

In an embodiment, forming or applying two or more piezoelectric filmlayers over the top surface of the substrate so that each of the two ormore piezoelectric film layers has a predefined residual stress thatsubstantially cancel each other out includes controlling one or both ofa pressure and a bias voltage during a deposition process for the eachof the two or more piezoelectric film layers.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of this disclosure will now be described, by way ofnon-limiting example, with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of one embodiment of a wireless device.

FIG. 2A is a schematic diagram of one embodiment of a packaged module.

FIG. 2B is a schematic diagram of a cross-section of the packaged moduleof FIG. 2A taken along the lines 2B-2B.

FIG. 3 is a top view of a piezoelectric MEMS circular diaphragmmicrophone.

FIG. 4 is a cross-sectional side view of the piezoelectric MEMSdiaphragm microphone of FIG. 3.

FIG. 5 is a top view of a piezoelectric MEMS rectangular diaphragmmicrophone.

FIG. 6 is a cross-sectional side view of the piezoelectric MEMSdiaphragm microphone of FIG. 5.

FIG. 7A is a cross-sectional side view of one step in the manufacture ofa piezoelectric MEMS diaphragm microphone.

FIG. 7B is a top view of the structure in FIG. 7A.

FIG. 8A is a cross-sectional side view of another step in themanufacture of a piezoelectric MEMS diaphragm microphone.

FIG. 8B is a top view of the structure in FIG. 8A.

FIG. 9A is a cross-sectional side view of another step in themanufacture of a piezoelectric MEMS diaphragm microphone.

FIG. 9B is a top view of the structure in FIG. 9A.

FIG. 10A is a cross-sectional side view of another step in themanufacture of a piezoelectric MEMS diaphragm microphone.

FIG. 10B is a top view of the structure in FIG. 10A.

FIG. 11A is a cross-sectional side view of another step in themanufacture of a piezoelectric MEMS diaphragm microphone.

FIG. 11B is a top view of the structure in FIG. 11A.

FIG. 12A is a cross-sectional side view of another step in themanufacture of a piezoelectric MEMS diaphragm microphone.

FIG. 12B is a top view of the structure in FIG. 12A.

FIG. 13A is a cross-sectional side view of another step in themanufacture of a piezoelectric MEMS diaphragm microphone.

FIG. 13B is a top view of the structure in FIG. 13A.

FIG. 14A is a cross-sectional side view of another step in themanufacture of a piezoelectric MEMS diaphragm microphone.

FIG. 14B is a top view of the structure in FIG. 14A.

FIG. 15A is a cross-sectional side view of another step in themanufacture of a piezoelectric MEMS diaphragm microphone.

FIG. 15B is a top view of the structure in FIG. 15A.

FIG. 16A is a cross-sectional side view of another step in themanufacture of a piezoelectric MEMS diaphragm microphone.

FIG. 16B is a top view of the structure in FIG. 16A.

FIG. 17 is a cross-sectional side view of another step in themanufacture of a piezoelectric MEMS diaphragm microphone.

FIG. 18 is a cross-sectional side view of another step in themanufacture of a piezoelectric MEMS diaphragm microphone.

FIG. 19A is a cross-sectional side view of another step in themanufacture of a piezoelectric MEMS diaphragm microphone.

FIG. 19B is a top view of the structure in FIG. 19A.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The following detailed description of certain embodiments presentsvarious descriptions of specific embodiments. However, the innovationsdescribed herein can be embodied in a multitude of different ways, forexample, as defined and covered by the claims. In this description,reference is made to the drawings were like reference numerals canindicate identical or functionally similar elements. It will beunderstood that elements illustrated in the figures are not necessarilydrawn to scale. Moreover, it will be understood that certain embodimentscan include more elements than illustrated in a drawing and/or a subsetof the elements illustrated in a drawing. Further, some embodiments canincorporate any suitable combination of features from two or moredrawings.

The International Telecommunication Union (ITU) is a specialized agencyof the United Nations (UN) responsible for global issues concerninginformation and communication technologies, including the shared globaluse of radio spectrum.

The 3rd Generation Partnership Project (3GPP) is a collaboration betweengroups of telecommunications standard bodies across the world, such asthe Association of Radio Industries and Businesses (ARIB), theTelecommunications Technology Committee (TTC), the China CommunicationsStandards Association (CCSA), the Alliance for TelecommunicationsIndustry Solutions (ATIS), the Telecommunications Technology Association(TTA), the European Telecommunications Standards Institute (ETSI), andthe Telecommunications Standards Development Society, India (TSDSI).

Working within the scope of the ITU, 3GPP develops and maintainstechnical specifications for a variety of mobile communicationtechnologies, including, for example, second generation (2G) technology(for instance, Global System for Mobile Communications (GSM) andEnhanced Data Rates for GSM Evolution (EDGE)), third generation (3G)technology (for instance, Universal Mobile Telecommunications System(UMTS) and High Speed Packet Access (HSPA)), and fourth generation (4G)technology (for instance, Long Term Evolution (LTE) and LTE-Advanced).

The technical specifications controlled by 3GPP can be expanded andrevised by specification releases, which can span multiple years andspecify a breadth of new features and evolutions.

In one example, 3GPP introduced carrier aggregation (CA) for LTE inRelease 10. Although initially introduced with two downlink carriers,3GPP expanded carrier aggregation in Release 14 to include up to fivedownlink carriers and up to three uplink carriers. Other examples of newfeatures and evolutions provided by 3GPP releases include, but are notlimited to, License Assisted Access (LAA), enhanced LAA (eLAA),Narrowband Internet-of-Things (NB-IOT), Vehicle-to-Everything (V2X), andHigh Power User Equipment (HPUE).

3GPP introduced Phase 1 of fifth generation (5G) technology in Release15 and plans to introduce Phase 2 of 5G technology in Release 16(targeted for 2019). Subsequent 3GPP releases will further evolve andexpand 5G technology. 5G technology is also referred to herein as 5G NewRadio (NR).

5G NR supports or plans to support a variety of features, such ascommunications over millimeter wave spectrum, beam forming capability,high spectral efficiency waveforms, low latency communications, multipleradio numerology, and/or non-orthogonal multiple access (NOMA). Althoughsuch RF functionalities offer flexibility to networks and enhance userdata rates, supporting such features can pose a number of technicalchallenges.

The teachings herein are applicable to a wide variety of communicationsystems, including, but not limited to, communication systems usingadvanced cellular technologies, such as LTE-Advanced, LTE-Advanced Pro,and/or 5G NR.

FIG. 1 is a schematic diagram of one embodiment of a wireless device100. The wireless device 100 can be, for example but not limited to, aportable telecommunication device such as a mobile cellular-typetelephone. The wireless device 100 can include one or more of a basebandsystem 101, a transceiver 102, a front end system 103, one or moreantennas 104, a power management system 105, a memory 106, a userinterface 107, a battery 108 (e.g., direct current (DC) battery), and amicrophone 300 (e.g., a piezoelectric MEMS diaphragm microphone). Otheradditional components, such as a speaker, display and keyboard canoptionally be connected to the baseband system 101. The battery 108 canprovide power to the wireless device 100. The microphone 300 can supplysignals to the baseband system 101.

It should be noted that, for simplicity, only certain components of thewireless device 100 are illustrated herein. The control signals providedby the baseband system 101 can control the various components within thewireless device 100. Further, the function of the transceiver 102 can beintegrated into separate transmitter and receiver components.

The wireless device 100 can communicate using a wide variety ofcommunications technologies, including, but not limited to, 2G, 3G, 4G(including LTE, LTE-Advanced, and LTE-Advanced Pro), 5G NR, WLAN (forinstance, Wi-Fi), WPAN (for instance, Bluetooth and ZigBee), WMAN (forinstance, WiMax), and/or GPS technologies.

The transceiver 102 generates RF signals for transmission and processesincoming RF signals received from the antennas 104. It will beunderstood that various functionalities associated with the transmissionand receipt of RF signals can be achieved by one or more components thatare collectively represented in FIG. 1 as the transceiver 102. In oneexample, separate components (for instance, separate circuits or dies)can be provided for handling certain types of RF signals.

The front end system 103 aids in conditioning signals transmitted toand/or received from the antennas 104. In the illustrated embodiment,the front end system 103 includes one or more power amplifiers (PAs)111, low noise amplifiers (LNAs) 112, filters 113, switches 114, andduplexers 115. However, other implementations are possible.

For example, the front end system 103 can provide a number offunctionalities, including, but not limited to, amplifying signals fortransmission, amplifying received signals, filtering signals, switchingbetween different bands, switching between different power modes,switching between transmission and receiving modes, duplexing ofsignals, multiplexing of signals (for instance, diplexing ortriplexing), or some combination thereof.

In certain implementations, the wireless device 100 supports carrieraggregation, thereby providing flexibility to increase peak data rates.Carrier aggregation can be used for both Frequency Division Duplexing(FDD) and Time Division Duplexing (TDD), and may be used to aggregate aplurality of carriers or channels. Carrier aggregation includescontiguous aggregation, in which contiguous carriers within the sameoperating frequency band are aggregated. Carrier aggregation can also benon-contiguous, and can include carriers separated in frequency within acommon band or in different bands.

The antennas 104 can include antennas used for a wide variety of typesof communications. For example, the antennas 104 can include antennasfor transmitting and/or receiving signals associated with a wide varietyof frequencies and communications standards.

In certain implementations, the antennas 104 support MIMO communicationsand/or switched diversity communications. For example, MIMOcommunications use multiple antennas for communicating multiple datastreams over a single radio frequency channel. MIMO communicationsbenefit from higher signal to noise ratio, improved coding, and/orreduced signal interference due to spatial multiplexing differences ofthe radio environment. Switched diversity refers to communications inwhich a particular antenna is selected for operation at a particulartime. For example, a switch can be used to select a particular antennafrom a group of antennas based on a variety of factors, such as anobserved bit error rate and/or a signal strength indicator.

The wireless device 100 can operate with beamforming in certainimplementations. For example, the front end system 103 can include phaseshifters having variable phase controlled by the transceiver 102.Additionally, the phase shifters are controlled to provide beamformation and directivity for transmission and/or reception of signalsusing the antennas 104. For example, in the context of signaltransmission, the phases of the transmit signals provided to theantennas 104 can be controlled such that radiated signals from theantennas 104 combine using constructive and destructive interference togenerate an aggregate transmit signal exhibiting beam-like qualitieswith more signal strength propagating in a given direction. In thecontext of signal reception, the phases can be controlled such that moresignal energy is received when the signal is arriving to the antennas104 from a particular direction. In certain implementations, theantennas 104 can include one or more arrays of antenna elements toenhance beamforming.

The baseband system 101 is coupled to the user interface 107 tofacilitate processing of various user input and output (I/O), such asvoice and data. The baseband system 101 provides the transceiver 102with digital representations of transmit signals, which the transceiver102 processes to generate RF signals for transmission. The basebandsystem 101 also processes digital representations of received signalsprovided by the transceiver 102. As shown in FIG. 1, the baseband system101 is coupled to the memory 106 of facilitate operation of the wirelessdevice 100.

The memory 106 can be used for a wide variety of purposes, such asstoring data and/or instructions to facilitate the operation of thewireless device 100 and/or to provide storage of user information.

The power management system 105 provides a number of power managementfunctions of the wireless device 100. In certain implementations, thepower management system 105 includes a PA supply control circuit thatcontrols the supply voltages of the power amplifiers 111. For example,the power management system 105 can be configured to change the supplyvoltage(s) provided to one or more of the power amplifiers 111 toimprove efficiency, such as power added efficiency (PAE).

As shown in FIG. 1, the power management system 105 receives a batteryvoltage from the battery 108. The battery 108 can be any suitablebattery for use in the wireless device 100, including, for example, alithium-ion battery.

FIG. 2A is a schematic diagram of one embodiment of a packaged module200. FIG. 2B is a schematic diagram of a cross-section of the packagedmodule 200 of FIG. 2A taken along the lines 2B-2B.

The packaged module 200 includes radio frequency components 201, asemiconductor die 202, surface mount devices 203, wirebonds 208, apackage substrate 230, and an encapsulation structure 240. One or moreof the surface mounted devices (SMDs) 203 can be a microphone 300 (e.g.,a piezoelectric MEMS diaphragm microphone). The package substrate 230includes pads 206 formed from conductors disposed therein. Additionally,the semiconductor die 202 includes pins or pads 204, and the wirebonds208 have been used to connect the pads 204 of the die 202 to the pads206 of the package substrate 220.

The semiconductor die 202 includes a power amplifier 245, which can beimplemented in accordance with one or more features disclosed herein.

The package substrate 230 can be configured to receive a plurality ofcomponents such as radio frequency components 201, the semiconductor die202 and the surface mount devices 203, which can include, for example,surface mount capacitors and/or inductors. In one implementation, theradio frequency components 201 include integrated passive devices(IPDs).

As shown in FIG. 2B, the packaged module 200 is shown to include aplurality of contact pads 232 disposed on the side of the packagedmodule 200 opposite the side used to mount the semiconductor die 202.Configuring the packaged module 200 in this manner can aid in connectingthe packaged module 200 to a circuit board, such as a phone board of amobile device. The example contact pads 232 can be configured to provideradio frequency signals, bias signals, and/or power (for example, apower supply voltage and ground) to the semiconductor die 202 and/orother components. As shown in FIG. 2B, the electrical connectionsbetween the contact pads 232 and the semiconductor die 202 can befacilitated by connections 233 through the package substrate 230. Theconnections 233 can represent electrical paths formed through thepackage substrate 220, such as connections associated with vias andconductors of a multilayer laminated package substrate.

In some embodiments, the packaged module 200 can also include one ormore packaging structures to, for example, provide protection and/orfacilitate handling. Such a packaging structure can include overmold orencapsulation structure 240 formed over the package substrate 230 andthe components and die(s) disposed thereon.

It will be understood that although the packaged module 200 is describedin the context of electrical connections based on wirebonds, one or morefeatures of the present disclosure can also be implemented in otherpackaging configurations, including, for example, flip-chipconfigurations.

Piezoelectric MEMS Microphone

FIGS. 3-4 show one implementation of a piezoelectricmicroelectromechanical systems (MEMS) diaphragm microphone 300A(hereinafter the “microphone”). The microphone 300A has a substrate 301.The substrate 301 is optionally made of Silicon. An insulation layer 311is disposed on a surface of the substrate 301. The insulation layer 311is optionally silicon dioxide. A first electrode 312 (e.g., a “bottom”electrode) is disposed on the oxide layer 311. One or more piezoelectricfilm layers 309 (e.g., multiple layers or multi-layer) are disposed onthe first electrode 312. In FIG. 4, two piezoelectric film layers 309are shown. At least one of the one or more piezoelectric film layers 309are optionally made of aluminum nitride (AlN). In anotherimplementation, at least one of the one or more piezoelectric filmlayers 309 are optionally made of aluminum scandium nitride (AIScN). Instill another implementation, at least one of the one or morepiezoelectric film layers 309 can be made of other suitable materials,such as zinc oxide. A second electrode 314 (e.g., a “middle” electrode)is disposed between at least two of the one or more piezoelectric filmlayers 309. A third electrode 315 (e.g., a “top” electrode) is disposedon top of the one or more piezoelectric film layers 309, and apassivation layer 318 is disposed over the third electrode 315 and atleast partially defines a top surface of the microphone 300A. In oneimplementation, the passivation layer 318 is optionally titanium nitride(TiN). The one or more piezoelectric film layers 309 define a diaphragm319.

With reference to FIG. 3, the microphone 300A can have a generallycircular or round shape. However, as discussed further below, themicrophone 300A can have other suitable shapes. The third electrode 315can include an outer circumferential electrode 302 and a centerelectrode 305. The outer circumferential electrode 302 can optionally bedivided into two or more portions 302A-302D by one or more gaps 303between the portions 302A-302D. The two or more portions 302A-302D canoptionally be connected in series with each other by one or moreconnection vias 304. Optionally, the gaps 303 can completely separatethe portions 302A-302D so that the portions 302A-302D are solelyconnected by the connection vias 304. The gaps 303 can advantageouslycontrol the amount of capacitance provided by the electrodes 302 (e.g.,if want a higher capacitance then fewer gaps 303 are provided; if want alower capacitance then more gaps 303 are provided). The reduction incapacitance (e.g., due to increased number of gaps 303) results inincreased sensitivity, and the increase in capacitance (e.g., due toreduced number of gaps 303) results in reduced sensitivity. Therefore,sensitivity and capacitance can advantageously be balanced as desiredvia the use of such gaps 303, 307 to divide the electrodes 302, 305. Thecenter electrode 305 can optionally be divided into two or more portions305A-305D by one or more gaps 307 between the portions 305A-305D. Thetwo or more portions 305A-305D can optionally be connected in serieswith each other by one or more connection vias 306 (e.g., which canfurther reduce the capacitance value of the electrode 302). Optionally,the gaps 307 can completely separate the portions 305A-305D so that theportions 305A-305D are solely connected by the connection vias 306. Thecenter electrode 305 can connect with the circumferential electrode 302by a connector 308. The microphone 300A can have one or more bond pads316 connected to the circumferential electrode 302.

The center electrode 305 can be spaced from the circumferentialelectrode 302 so that the center electrode 305 is substantially centeredrelative to the circumferential electrode 302 (e.g., both electrodes302, 305 have the same central axis), with at least a portion of thediaphragm 319 extending between the circumferential electrode 302 andthe center electrode 305. As shown in FIGS. 3-4, the diaphragm 319 canextend beneath the circumferential electrode 302 and beneath the centerelectrode 305. A through hole 310 can be formed (e.g., etched) in thediaphragm 319 (e.g., in the one or more piezoelectric film layers 309that define the diaphragm 319) at a location between the circumferentialelectrode 302 and the center electrode 305. The through hole 310 canextend from a top surface of the diaphragm 319 to a bottom surface ofthe diaphragm 319 to thereby extend completely through the diaphragm319. The microphone 300A can have an opening 320 in the substrate 301that is located underneath the diaphragm 319, which allows the diaphragm319 to move (e.g., deflect).

With continued reference to FIG. 3, the electrodes 302, 305 areadvantageously located (e.g., electrode 302 along the periphery andelectrode 305 at the center of the diaphragm structure 319) where thehighest stress, therefore highest output voltage or electrical energyvia piezoelectric effect, is induced by sound pressure exerted on thediaphragm 319 (e.g., via air pressure delivered through the opening 320toward the diaphragm 319). As discussed further below, the one or morepiezoelectric film layers 309 can be multiple layers (e.g., two), eachhaving a predefined residual stress, where such residual stresses of themultiple layers balance (e.g., cancel each other out) in the combineddiaphragm structure 319, thereby advantageously providing a diaphragmstructure 319 with approximately zero (e.g., zero) residual stress.

FIGS. 5-6 show another implementation of a piezoelectricmicroelectromechanical systems (MEMS) diaphragm microphone 300B(hereinafter the “microphone”). The microphone 300B has a substrate301′. The substrate 301′ is optionally made of Silicon. An insulationlayer 311′ is disposed on a surface of the substrate 301′. Theinsulation layer 311′ is optionally Silicon dioxide. A first electrode312′ (e.g., a “bottom” electrode) is disposed on the oxide layer 311′.One or more piezoelectric film layers 309′ (e.g., multiple layers ormulti-layer) are disposed on the first electrode 312′. In FIG. 6, twopiezoelectric film layers 309′ are shown. At least one of the one ormore piezoelectric film layers 309′ are optionally made of aluminumnitride (AlN). In another implementation, at least one of the one ormore piezoelectric film layers 309′ are optionally made of aluminumscandium nitride (AIScN). A second electrode 314′ (e.g., a “middle”electrode) is disposed between at least two of the one or morepiezoelectric film layers 309′. A third electrode 315′ (e.g., a “top”electrode) is disposed on top of the one or more piezoelectric filmlayers 309′, and a passivation layer 318′ is disposed over the thirdelectrode 315′ and at least partially defines a top surface of themicrophone 300B. In one implementation, the passivation layer 318′ isoptionally titanium nitride (TiN). The one or more piezoelectric filmlayers 309′ define a diaphragm 319′.

With reference to FIG. 5, the microphone 300B can have a generallyrectangular (e.g., square) shape. However, the microphone 300B can haveother suitable shapes. The third electrode 315′ can include one or moreside electrodes 302′ adjacent one or more sides of the diaphragm 319′.In FIG. 5, the third electrode 315′ includes four side electrodes 302′,each adjacent a side of the rectangular (e.g., square) shape of thediaphragm 319′. Each of the side electrodes 302′ can optionally bedivided into two or more portions 302A′, 302B′, 302C′ by one or moregaps 303′ between the portions 302A′, 302B′, 302C′. The gaps 303′ canadvantageously control the amount of capacitance provided by theelectrodes 302′ (e.g., if want a higher capacitance then fewer gaps 303′are provided; if want a lower capacitance then more gaps 303′ areprovided). The reduction in capacitance (e.g., due to increased numberof gaps 303) results in increased sensitivity, and the increase incapacitance (e.g., due to reduced number of gaps 303) results in reducedsensitivity. Therefore, sensitivity and capacitance can advantageouslybe balanced as desired via the use of such gaps 303′, 307′ to divide theelectrodes 302′. The two or more portions 302A′, 302B′, 302C′ canoptionally be connected in series with each other by one or moreconnection vias 304′ (e.g., which can further reduce the capacitancevalue of the electrode 302′). Optionally, the gaps 303′ can completelyseparate the portions 302A′, 302B′, 302C′ so that the portions 302A′,302B′, 302C′ are solely connected by the connection vias 304′. In oneimplementation, a center electrode (e.g., divided into two or moreelectrodes connected in series), similar to the center electrode 305with electrode portions 305A-305D in FIG. 3, can optionally be added tothe rectangular diaphragm 319′ to improve output energy and provide moreflexibility for balancing sensitivity and capacitance. The microphone300B can have one or more bond pads 316′ connected to two of the one ormore side electrodes 302′.

As shown in FIGS. 5-6, the diaphragm 319′ can extend beneath the sideelectrodes 302′ and across a center portion of the microphone 300Bbetween opposite side electrodes 302′. A through hole 310′ can be formed(e.g., etched) in the diaphragm 319′ (e.g., in the one or morepiezoelectric film layers 309′ that define the diaphragm 319′) at alocation between opposing side electrodes 302′. The through hole 310′can extend from a top surface of the diaphragm 319′ to a bottom surfaceof the diaphragm 319′ to thereby extend completely through the diaphragm319′. The microphone 300B can have an opening 320′ in the substrate 301′that is located underneath the diaphragm 319′, which allows thediaphragm 319′ to move.

With continued reference to FIG. 5, the electrodes 302′ areadvantageously located where the highest stress is induced, thereforehighest output voltage or electrical energy via piezoelectric effect,(e.g., along the sides of the diaphragm structure 319′) by soundpressure exerted on the diaphragm 319′ (e.g., via air pressure deliveredthrough the opening 320′ toward the diaphragm 319′). As discussedfurther below, the one or more piezoelectric film layers 309′ can bemultiple layers (e.g., two), each having a predefined residual stress,where such residual stresses of the multiple layers balance (e.g.,cancel each other out) in the combined diaphragm structure 319′, therebyadvantageously providing a diaphragm structure 319′ with approximatelyzero (e.g., zero) residual stress.

The through holes 310, 310′ in the diaphragms 319, 319′ of themicrophones 300A, 300B can advantageously allow the low frequency rolloff of the microphone 300A, 300B to be defined substantially precisely(e.g., at approximately 85 Hz±15 Hz, such as for cell phoneapplications). That is, the size of the through hole 310, 310′ canadvantageously provide the desired value for the low frequency roll off(e.g., there is a correlation between the size of the through hole andthe value of the low frequency roll off).

The diaphragm 319, 319′ of the microphone 300A, 300B has a multi-layerstructure (e.g., one or more piezoelectric film layers 309, such as twolayers, three layers, four layers, etc.) that advantageously provideshigher sensitivity (about 2-3 dB higher) and better low-frequencyroll-off control (−3 dB frequency) than cantilever structures. Thediaphragm 319, 319′ with multi-layers structure also has highersensitivity than a single layer diaphragm. The one or more piezoelectricfilm layers 309, 309′ (e.g., two layers, three layers, four layers, fivelayers, etc.) of the diaphragm 319, 319′ in the microphone 300A, 300Beach have residual stresses (e.g., pre-defined residual stressesintroduced during the deposition process) that advantageously canceleach other out to provide a substantially flat (e.g., flat) diaphragm309, 309′ that is substantially residual-stress free (e.g., so that theoverall residual stress is approximately zero). The one or morepiezoelectric film layers 309, 309′ can in one implementation be an evennumber of layers (e.g., two, four, six, etc.). In anotherimplementation, the one or more piezoelectric film layers 309, 309′ canbe an odd number of layers (e.g., three, five, seven, etc.).

FIGS. 7A-19B show steps of a method 400 of manufacturing a piezoelectricMEMS diaphragm microphone. Though FIGS. 7A-19B show the method 400 formanufacturing the microphone 300A, one of skill in the art willrecognize that the method 400 can also be used to manufacture themicrophone 300B. FIGS. 7A-7B show a cross-sectional view and a top view,respectively, of the step of oxidizing 402 one or both of a top side anda bottom side of a substrate (such as the substrate 301, 301′) to forman oxidation layer, such as oxidation layer 311, 311′. Optionally, theoxidizing can be performed with a thermal oxidation furnace. In oneimplementation, the oxidation layer (e.g., oxidation layer 311, 311′)optionally has a thickness of approximately 2-3 μm. The top oxidationlayer can provide isolation between the substrate 301, 301′ and the oneor more piezoelectric film layers 309, 309′. The bottom oxidation layercan be used as a hard mask to define a window for later etching theopening 320, 320′ into the microphone 300A, 300B. The substrate 301,301′ can be made of Silicon, and the oxidation layers can be of Silicondioxide.

FIGS. 8A-8B show a cross-sectional view and a top view, respectively, ofthe step of forming or applying 404 (e.g., and patterning, such as usingwet etching, dry etching, etc.) a first electrode (e.g., the “bottom”electrode), such as the first electrode 312, 312′ on the top oxidationlayer (e.g., oxidation layer 311, 311′). Optionally, the first electrodecan be formed or applied 404 using a sputter machine and patterned bydry etching (e.g., using Reactive Ion Etch (RIE) and/or InductivelyCoupled Plasma (ICP) etch). In one implementation, the first electrode(e.g., first electrode 312, 312′) optionally has a thickness ofapproximately 30 nm.

FIGS. 9A-9B show a cross-sectional view and a top view, respectively, ofthe step of forming or applying 406 (e.g., via deposition) 406 one ormore piezoelectric film layers, such as piezoelectric film layers 309,on top (e.g., adjacent to, attached to) the first electrode. Optionally,the one or more piezoelectric film layers are formed or applied using asputter machine. As discussed above, the one or more piezoelectric filmlayers can optionally be made of aluminum nitride (AlN) or aluminumscandium nitride (AIScN). In one implementation, the one or morepiezoelectric film layers can optionally have a total thickness ofapproximately 500 nm. Optionally, the one or more piezoelectric filmlayers are applied so that each layer has a predefined residual stress.For example, where the piezoelectric material is aluminum nitride, oneor both of the pressure of the deposition chamber and the radiofrequencybias voltage applied can be controlled to provide a pre-defined residualstress to each of the piezoelectric film layers applied (e.g., residualstress can be gradually controlled using pressure and/or bias voltageduring the deposition process based on a known correlation betweenresidual stress and one or both of pressure and bias voltage).

FIGS. 10A-10B show a cross-sectional view and a top view, respectivelyof the step of forming or applying 408 (e.g., and patterning, such asusing wet etching, dry etching, etc.) a second electrode (e.g., the“middle” electrode), such as the second electrode 314, 314′ onto (e.g.,adjacent to, attached to) the one or more piezoelectric film layers,such as the piezoelectric film layers 309. Optionally, the secondelectrode can be formed or applied 408 using a sputter machine andpatterned by dry etching (e.g., using Reactive Ion Etch (ME) and/orInductively Coupled Plasma (ICP) etch). In one implementation, thesecond electrode (e.g., second electrode 314, 314′) optionally has athickness of approximately 30 nm.

FIGS. 11A-11B show a cross-sectional view and a top view, respectively,of the step of forming or applying 410 (e.g., via deposition) one ormore piezoelectric film layers, such as piezoelectric film layers 309,on top (e.g., adjacent to, attached to) of the second electrode.Optionally, the one or more piezoelectric film layers are formed orapplied using a sputter machine. As discussed above, the one or morepiezoelectric film layers can optionally be made of aluminum nitride(AlN) or aluminum scandium nitride (AIScN). In one implementation, theone or more piezoelectric film layers can optionally have a totalthickness of approximately 500 nm. Optionally, the one or morepiezoelectric film layers are applied so that each layer has apredefined residual stress. For example, where the piezoelectricmaterial is aluminum nitride, one or both of the pressure of thedeposition chamber and the radiofrequency bias voltage applied can becontrolled to provide a pre-defined residual stress to each of thepiezoelectric film layers applied (e.g., residual stress can begradually controlled using pressure and/or bias voltage during thedeposition process based on a known correlation between residual stressand one or both of pressure and bias voltage).

FIGS. 12A-12B show a cross-sectional and a top view, respectively of thestep of forming or applying 412 a third electrode (e.g., a “top”electrode) onto the one or more piezoelectric layers that are disposedon top of the second electrode. Optionally, the third electrode can beformed or applied 412 using a sputter machine and patterned by dryetching (e.g., using Reactive Ion Etch (ME) and/or Inductively CoupledPlasma (ICP) etch). In one implementation, the third electrode (e.g.,third electrode 315, 315′) optionally has a thickness of approximately30 nm.

FIGS. 13A-13B show a cross-sectional and a top view, respectively of thestep of forming or applying 414 a passivation layer, such as thepassivation layer 318, 318′, on top of (e.g., adjacent to, attached to)the third electrode. Optionally, the passivation layer can be formed orapplied 414 using a sputter machine or a Chemical Vapor Deposition (CVD)machine. In one implementation, the passivation layer optionally has athickness of approximately 50 nm.

FIGS. 14A-14B show a cross-sectional and a top view, respectively, ofthe step of forming (e.g., etching) 416 one or more vias through thepassivation layer and one or more piezoelectric film layers. The figuresshow one via etched through one of (e.g., half of) the piezoelectricfilm layers and another via etched through two of (e.g., all of) thepiezoelectric film layers. Optionally, the vias can be etched using anInductively Coupled Plasma (ICP) etch machine and process.

FIGS. 15A-15B show a cross-sectional view and a top view, respectively,of the step of forming or applying 418 (e.g., via deposition) one ormore bond pads, such as bond pads 316, 316′, and patterning them.Optionally, the one or more bond pads can be formed or applied 418 usinga sputter machine, or an E-beam evaporator and lift-off process. Thepassivation layer 318, 318′ can serve to protect the top of themicrophone 300A, 300B.

FIGS. 16A-16B show a cross-sectional view and a top view, respectively,of the step of forming or applying 420 a top protection layer (e.g., asilicon dioxide layer) on top of (e.g., adjacent to, attached to) thepassivation layer. Optionally, the top protection layer can be formed orapplied 420 using a Plasma Enhanced Chemical Vapor Deposition (PECVD)machine and process. In one implementation, the top protection layeroptionally has a thickness of approximately 2 μm.

FIG. 17 shows a cross-sectional view of the step of patterning 422 andetching 424 the oxide layer on the bottom of the substrate. Optionally,the patterning and etching 422, 424 of the oxide layer on the bottom ofthe substrate can be performed using a Reactive Ion Etch (RIE) and/orInductively Coupled Plasma (ICP) etch machine and process.

FIG. 18 shows a cross-sectional view of the step of etching 426 of thesubstrate to create an opening, such as the opening 320, 320′,underneath the diaphragm. Optionally, the etching 426 of the substratecan be performed using a Deep Reactive Ion Etching (DRIE) machine andprocess.

FIGS. 19A and 19B show a cross-sectional view and a top view,respectively, of the step of removing 428 (e.g., etching) the protectionlayer, oxide layer on the bottom of the substrate, and oxide layer underthe first electrode. Optionally, the removing (e.g., etching) 428 of theprotection layer, oxide layer on the bottom of the substrate and oxidelayer under the first electrode can be performed using a Vapor HydrogenFluoride (VHF) etch machine and process. The opening 320, 320′ allowssound pressure to pass therethrough to exert a force on the diaphragm319, 319′ (e.g., on the first or bottom electrode 312, 312′) to deflectthe diaphragm 319, 319′.

In use, the microphone structure 300A, 300B is mounted on a printedcircuit board (PCB) so that the opening 320, 320′ is disposed over orotherwise generally aligned with an opening in the PCB through whichsound pressure enters into the opening 320, 320′ to deflect thediaphragm 319, 319′ as discussed above.

While certain embodiments of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the disclosure. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms. Furthermore, various omissions, substitutions and changes in thesystems and methods described herein may be made without departing fromthe spirit of the disclosure. The accompanying claims and theirequivalents are intended to cover such forms or modifications as wouldfall within the scope and spirit of the disclosure. Accordingly, thescope of the present inventions is defined only by reference to theappended claims.

Features, materials, characteristics, or groups described in conjunctionwith a particular aspect, embodiment, or example are to be understood tobe applicable to any other aspect, embodiment or example described inthis section or elsewhere in this specification unless incompatibletherewith. All of the features disclosed in this specification(including any accompanying claims, abstract and drawings), and/or allof the steps of any method or process so disclosed, may be combined inany combination, except combinations where at least some of suchfeatures and/or steps are mutually exclusive. The protection is notrestricted to the details of any foregoing embodiments. The protectionextends to any novel one, or any novel combination, of the featuresdisclosed in this specification (including any accompanying claims,abstract and drawings), or to any novel one, or any novel combination,of the steps of any method or process so disclosed.

Furthermore, certain features that are described in this disclosure inthe context of separate implementations can also be implemented incombination in a single implementation. Conversely, various featuresthat are described in the context of a single implementation can also beimplemented in multiple implementations separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations, one or more features from a claimedcombination can, in some cases, be excised from the combination, and thecombination may be claimed as a subcombination or variation of a subcombination.

Moreover, while operations may be depicted in the drawings or describedin the specification in a particular order, such operations need not beperformed in the particular order shown or in sequential order, or thatall operations be performed, to achieve desirable results. Otheroperations that are not depicted or described can be incorporated in theexample methods and processes. For example, one or more additionaloperations can be performed before, after, simultaneously, or betweenany of the described operations. Further, the operations may berearranged or reordered in other implementations. Those skilled in theart will appreciate that in some embodiments, the actual steps taken inthe processes illustrated and/or disclosed may differ from those shownin the figures. Depending on the embodiment, certain of the stepsdescribed above may be removed, others may be added. Furthermore, thefeatures and attributes of the specific embodiments disclosed above maybe combined in different ways to form additional embodiments, all ofwhich fall within the scope of the present disclosure. Also, theseparation of various system components in the implementations describedabove should not be understood as requiring such separation in allimplementations, and it should be understood that the describedcomponents and systems can generally be integrated together in a singleproduct or packaged into multiple products.

For purposes of this disclosure, certain aspects, advantages, and novelfeatures are described herein. Not necessarily all such advantages maybe achieved in accordance with any particular embodiment. Thus, forexample, those skilled in the art will recognize that the disclosure maybe embodied or carried out in a manner that achieves one advantage or agroup of advantages as taught herein without necessarily achieving otheradvantages as may be taught or suggested herein.

Conditional language, such as “can,” “could,” “might,” or “may,” unlessspecifically stated otherwise, or otherwise understood within thecontext as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements, and/or steps. Thus, such conditional language is notgenerally intended to imply that features, elements, and/or steps are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or without userinput or prompting, whether these features, elements, and/or steps areincluded or are to be performed in any particular embodiment.

Conjunctive language such as the phrase “at least one of X, Y, and Z,”unless specifically stated otherwise, is otherwise understood with thecontext as used in general to convey that an item, term, etc. may beeither X, Y, or Z. Thus, such conjunctive language is not generallyintended to imply that certain embodiments require the presence of atleast one of X, at least one of Y, and at least one of Z.

Language of degree used herein, such as the terms “approximately,”“about,” “generally,” and “substantially” as used herein represent avalue, amount, or characteristic close to the stated value, amount, orcharacteristic that still performs a desired function or achieves adesired result. For example, the terms “approximately”, “about”,“generally,” and “substantially” may refer to an amount that is withinless than 10% of, within less than 5% of, within less than 1% of, withinless than 0.1% of, and within less than 0.01% of the stated amount. Asanother example, in certain embodiments, the terms “generally parallel”and “substantially parallel” refer to a value, amount, or characteristicthat departs from exactly parallel by less than or equal to 15 degrees,10 degrees, 5 degrees, 3 degrees, 1 degree, or 0.1 degree.

The scope of the present disclosure is not intended to be limited by thespecific disclosures of preferred embodiments in this section orelsewhere in this specification, and may be defined by claims aspresented in this section or elsewhere in this specification or aspresented in the future. The language of the claims is to be interpretedbroadly based on the language employed in the claims and not limited tothe examples described in the present specification or during theprosecution of the application, which examples are to be construed asnon-exclusive.

Of course, the foregoing description is that of certain features,aspects and advantages of the present invention, to which variouschanges and modifications can be made without departing from the spiritand scope of the present invention. Moreover, the shielded inductor neednot feature all of the objects, advantages, features and aspectsdiscussed above. Thus, for example, those of skill in the art willrecognize that the invention can be embodied or carried out in a mannerthat achieves or optimizes one advantage or a group of advantages astaught herein without necessarily achieving other objects or advantagesas may be taught or suggested herein. In addition, while a number ofvariations of the invention have been shown and described in detail,other modifications and methods of use, which are within the scope ofthis invention, will be readily apparent to those of skill in the artbased upon this disclosure. It is contemplated that various combinationsor subcombinations of these specific features and aspects of embodimentsmay be made and still fall within the scope of the invention.Accordingly, it should be understood that various features and aspectsof the disclosed embodiments can be combined with or substituted for oneanother in order to form varying modes of the discussed shieldedinductor.

What is claimed is:
 1. A method of making a piezoelectricmicroelectromechanical systems diaphragm microphone, comprising:oxidizing a top surface and a bottom surface of a substrate to form atop oxidation layer and a bottom oxidation layer; forming or applyingtwo or more piezoelectric film layers over the top surface of thesubstrate so that each of the two or more piezoelectric film layers havea predefined residual stress that substantially cancel each other out,the two or more piezoelectric film layers defining a substantially flatdiaphragm structure with substantially zero residual stress; forming orapplying one or more electrodes over the two or more piezoelectric filmlayers; and etching the bottom oxidation layer and substrate to form anopening in the substrate that allows sound pressure to travel throughthe opening to deflect the diaphragm structure.
 2. The method of claim 1wherein the diaphragm structure has a circular shape.
 3. The method ofclaim 2 wherein forming or applying the one or more electrodes over thetwo or more piezoelectric film layers includes forming or applying acircumferential electrode over a circumference of the diaphragmstructure and forming or applying a center electrode generally over acenter of the diaphragm structure, at least a portion of the centerelectrode spaced apart from the circumferential electrode.
 4. The methodof claim 1 wherein the diaphragm structure has a rectangular shape. 5.The method of claim 4 wherein forming or applying the one or moreelectrodes over the two or more piezoelectric film layers includesforming or applying a plurality of side electrodes disposed adjacentcorresponding side edges of the diaphragm structure, the plurality ofside electrodes spaced apart from each other and disposed around an areaof the diaphragm structure that extends between the plurality of sideelectrodes.
 6. The method of claim 1 further comprising dividing the oneor more electrodes into two or more electrode portions by forming one ormore gaps between the electrode portions to provide a microphone with adesired sensitivity and capacitance.
 7. The method of claim 6 furthercomprising connecting each pair of the two or more electrode portions inseries with a connection via.
 8. The method of claim 1 furthercomprising forming a through hole in the diaphragm structure from a topsurface of the diaphragm structure to a bottom surface of the diaphragmstructure to define a low frequency roll off for the microphone.
 9. Themethod of claim 1 further comprising forming or applying a bottomelectrode over the top surface of the substrate prior to forming orapplying the two or more piezoelectric film layers.
 10. The method ofclaim 9 further comprising forming or applying a middle electrodebetween two of the two or more piezoelectric film layers.
 11. The methodof claim 1 further comprising forming or applying a passivation layerover the one or more electrodes disposed over the two or morepiezoelectric film layers.
 12. The method of claim 1 wherein forming orapplying two or more piezoelectric film layers over the top surface ofthe substrate so that each of the two or more piezoelectric film layershave a predefined residual stress that substantially cancel each otherout includes controlling one or both of a pressure and a bias voltageduring a deposition process for the each of the two or morepiezoelectric film layers
 13. A method of making a radiofrequencymodule, comprising: forming or providing a printed circuit board thatincludes a substrate layer; forming or providing one or morepiezoelectric microelectromechanical systems diaphragm microphones via aprocess comprising (a) oxidizing a top surface and a bottom surface of asubstrate to form a top oxidation layer and a bottom oxidation layer,(b) forming or applying two or more piezoelectric film layers over thetop surface of the substrate so that each of the two or morepiezoelectric film layers have a predefined residual stress thatsubstantially cancel each other out, the two or more piezoelectric filmlayers defining a substantially flat diaphragm structure withsubstantially zero residual stress, (c) forming or applying one or moreelectrodes over the two or more piezoelectric film layers, and (d)etching the bottom oxidation layer and substrate to form an opening inthe substrate that allows sound pressure to travel through the openingto deflect the diaphragm structure; and mounting the one or morepiezoelectric microelectromechanical systems diaphragm microphones onthe printed circuit board.
 14. The method of claim 13 wherein thediaphragm structure has a circular shape.
 15. The method of claim 14wherein forming or applying the one or more electrodes over the two ormore piezoelectric film layers includes forming or applying acircumferential electrode over a circumference of the diaphragmstructure and forming or applying a center electrode generally over acenter of the diaphragm structure, at least a portion of the centerelectrode spaced apart from the circumferential electrode.
 16. Themethod of claim 13 wherein the diaphragm structure has a rectangularshape.
 17. The method of claim 16 wherein forming or applying the one ormore electrodes over the two or more piezoelectric film layers includesforming or applying a plurality of side electrodes disposed adjacentcorresponding side edges of the diaphragm structure, the plurality ofside electrodes spaced apart from each other and disposed around an areaof the diaphragm structure that extends between the plurality of sideelectrodes.
 18. The method of claim 13 further comprising dividing theone or more electrodes into two or more electrode portions by formingone or more gaps between the electrode portions to provide a microphonewith a desired sensitivity and capacitance.
 19. The method of claim 18further comprising connecting each pair of the two or more electrodeportions in series with a connection via.
 20. The method of claim 13further comprising forming a through hole in the diaphragm structurefrom a top surface of the diaphragm structure to a bottom surface of thediaphragm structure to define a low frequency roll off for themicrophone.